an epic struggle between life and technology

Toyota 1MZ deep sump baffled oil pan

Our previous track experience indicated strongly that a better oil pan was needed for the 1MZ. Although we installed an oil pressure accumulator our first engine still barely lased an hour and the second about 10 minutes. The 1MZ features a very poor pan design for performance driving. The pan is very shallow and wide. The oil depth when the engine is full is only around 2″ above the bottom of the pan! It is no surprise that this causes issues!

The first step of this project was to make the pan deeper. A deeper pan will increase capacity without increasing windage and will also give us more room to play with the baffling. With the pickup placed deeper in the oil it should also help it to stay covered. I added around .8″ of depth to the pan. This doesn’t sound like much but with the huge cross section of the pan that adds around a quart of oil! With our accumulator and this deep pan we should be around 7 or 8 quarts now when full.

I started by sectioning the pan around an inch and a half from the bottom of the pan. I cut it parallel to the ground since that is the direction I wanted to extend it. I cut it right at the point the bottom radius ended, which gave adequate space from the cut to the flange even at the shortest part. The pan it a bit odd in design since the base of the engine is perpendicular to the V of the engine but it is canted around 15 degrees from vertical in the car and the pan base is parallel to the ground.

The cutline height was selected to give some room next to the flange but also not cut through the radius.

Two oil pans marked and ready for cutting.

Sectioned oil pan

Sectioned oil pan

Sectioned oil pans

Sectioned oil pan

Flange extension welded onto the bottom half

Flange welded onto bottom half

Oil pan whole again, tacked together

Oil pan whole again, tacked together

Welding finished

Welding finished

Welding finished

Welding finished

Once sectioned I just took a long strip of steel and started bending and tacking it around the edge trying to keep it nice and parallel.

Now the hard part, reattaching the top! I used the little sheet metal edge clamps (from Harbor Freight) to help hold everything in place. Although it worked the gap that they leave is somewhat large. I didn’t have any trouble filling it but it ended up a bit messier than I originally wanted. In any case some tweaking is needed on this step.

Now that the pan is extended I started playing with the baffling design. I started with a basic “diamond” center chamber which will have flapper doors in it facing inwards. I positioned it near the center of the pan and made it about 4″ on a side. Then added baffles from the corners out to the edges of the pan. I made the baffles 2.75″ high which meant that the top of the baffles would almost perfectly line up with the lowest part of the engine flange. I knew I wanted to put a flat plate on top of the baffles parallel to the ground and wanted it to stay below the edge of the pan. Normally I would have put it a bit higher but I think this should be adequate. The space under the plate will hold around 4qts of oil so there will be some sitting above it when the car is at rest. I may add some additional baffling to the top of this plate to direct oil to the center hole as well.

Another view of pickup position.

Aluminum plate mocked up to position the pickup where it normally sits in the engine.

Top plate with hole added for the pickup.

Top plate baffle on top of the mockup.

Mockup of the oil pan baffles in cardboard. The oil chamber is a diamond in the center of the pan.

Now I took a shot at relocating the oil pickup to the center of the oil chamber. The pickup is also a bit of a strange geometry due to the tilted engine so I built a sheet metal bracket to hold it approximately where it goes on the engine. I need to rotate it around 45 degrees and then probably extend the reach slightly. Then it will have to drop around .8″ to be close to the bottom again after the deep sump. One potential issue here is that since the pickup is so large the flapper doors may hit it and not be able to open all the way. The pickup is exactly 3″ in outer diameter and largest at the base. Once the pickup is relocated I’ll take another look at this. I may need to enlarge the center chamber slightly to leave enough room for the doors to swing.